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Old Nov 30, 2009, 03:35 PM
Veni, Vidi, Feci
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Wait- of course! This is the perfect place to use that rapid prototyping stuff:
http://www.rcgroups.com/forums/showthread.php?t=1088812

My DUKW never really was finished, partly due to time and other projects, partly because a number of details were just too much grief to make... but I could print those scale rims and hubs, the winch, the tow hook, and a bunch of other stuff, maybe even axle housings!
Hmm, still have to deal with the time issue...
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Old Nov 30, 2009, 04:44 PM
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The rapid prototyping only works for detail parts, right? couldn't do the running gear quite yet.
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Old Nov 30, 2009, 04:56 PM
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Quote:
Originally Posted by patmat2350 View Post
One thing to watch for- climbing out takes a lot of driveline torque, so design accordingly.
good to know. i definitely want this to be able to drive in and out of the creek.

i was thinking of using RC buggy suspension, or similar. buggy might be too aggressive for a scale look, but the traction would help.

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Also would be neat to have authentic bar tread tires... these airplane tires have no grab.
what about using the tires from a rc buggy? they are pretty narrow so the look would be similar.
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Old Nov 30, 2009, 04:59 PM
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Quote:
Originally Posted by CG Bob View Post
IIRC the propellor drive has a 6:1 reduction and the wheel drive motor has an 11:1 reduction.
how does the gear reduction effect "power" in the water? can the dukw handle a creek with a current?
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Old Nov 30, 2009, 05:04 PM
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cg bob, is that your duck on the loyalhanna site?
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Old Nov 30, 2009, 06:09 PM
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Quote:
Originally Posted by daemuon View Post
how does the gear reduction effect "power" in the water? can the dukw handle a creek with a current?
The gear reduction is needed to get the best torgue (and power) from the prop. In the water, the DUKW has appropriate scale speed - using the TLAR principle; same for speed on land. I've only run it in lakes and haven't had to try to go cross current in a creek. How much current does your creek have?

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Originally Posted by daemuon
cg bob, is that your duck on the loyalhanna site?
Yes it is.

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Originally Posted by daemuon
what about using the tires from a rc buggy? they are pretty narrow so the look would be similar.
Depending on the scale, they might work. I took one of my DUKW wheels into the LHS where I work and compared it to some of the newer truck and rock crawler wheels available - all of the ones we have in stock are too wide. The tires for the new Traxxas 1:16 scale Slash are almost the right width, but are the wrong diameter.
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Old Nov 30, 2009, 06:38 PM
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don't know how to relate the current... it's a stream about 15 to 20 feet in spots, 3 feet deep in the rapids and narrow portions and about 6 feet at the 2 swimming holes.

the swimming holes have very little current, and that's usually where i go. but if it goes past there i don't want to go swimming

as for scale, maybe i'll find my running gear and tires and work up the scale from that.
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Old Nov 30, 2009, 07:01 PM
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DUKWs don't take too kindly to rough water... I almost swamped mine in a fairly mild creek.

Rapid proto: Yes, some of the materials are pretty strong, and with proper design (robust), could do something like an axle housing. Need to allow for clean-up machining stock.

Tires- RC buggy tires are fine for a toy... you won't find anything skinny enough to look "scale".

Driveline- rock crawler gear should work... but watch for slip clutches, they are probably set too low.
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Old Dec 01, 2009, 05:01 PM
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can the rapid proto do rubber??? since we can't find the correct tires maybe they could be made.

or maybe get one done in plastic as a master, but could a mold be made from that then pour rubber? one of my uncles tractors had solid tires so it might work for a scale model.

i thought about doing one of the more modern amphibs that have tracks like a tank but they don't have as much "style" as a dukw.
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Old Dec 02, 2009, 11:30 AM
GILL
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I just saw this thread. I didn't build a Duk but I did an Amphicar, all scratch and no lathe work (didnít have one at the time). Pat you have seen my car at Toledo (3rd place) and at Cabin fever ( same year as the Fitch).
Like the full size it is rear wheel drive with twin screws. I use a 500 size motor for the land power and 2 400's for the props, runs great. The trick like with the full size is to have speed when you head for land. Functions include head lights, tail lights, turn signals, running lights, horn, and roof up/down.
Since the front wheels steer n the water I have also added differential speed on the props. This cuts the water turns from over 25 ft to 5-6.
The land drive is a toothed belt in side the right rear wheel with a live axel.
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Old Dec 02, 2009, 12:08 PM
Veni, Vidi, Feci
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You have to show us the innards, John!
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Old Dec 02, 2009, 02:35 PM
GILL
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I'll dig her out and pull the rear seat, open the hood, and trunk. Then take a few pic's. The motors and speed controls sit under the roof deck & rear seat. The receiver and all electronics including the 4.8 volt radio battery are in the front. The 6 cell drive battery and on off switch is in the trunk. You pull on the exhaust pipe to switch on, just push for off. I have a micro geared motor mounted for the wipers I just have not hooked them up yet.
Maybe by Monday I'll have the pictures.
She does about 20 mph on land and about 6 in the water.
I did make a ramp to get in and out of our pond. We have a block wall all the way around. The ramp has a "U" shaped rod at the water end and the end of the ramp is weighted. I can set the depth of the end of the ramp. The top of the ramp is hinged to sit flat on top of the blocks. The ramp angle has a very porous sanding grit on it and 1/2 in high walls. It takes a good eye to hit center on a 12 in wide ramp.
I love to watch the kids faces when I drive along side the pond and just make a turn to go in to the water.
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Old Dec 02, 2009, 06:26 PM
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pat beat me to it!

i'm interested in the tires too. from the SOSS pic it looks like they are tall and narrow, but what kind of tread is on them?

that is a sweet looking car!
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Old Dec 02, 2009, 06:33 PM
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it looks like shapeways.com can do nylon and bronze infused stainless.

so i could have them do housings but i don't know if nylon would be good for tires.
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Old Dec 02, 2009, 06:48 PM
Submarines, etc.
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daemuon,

I would "assume" -- note the quotes, if you made your DUKW 1:16th scale, or there abouts, you could use a lot of the tamiya semi-tractor truck parts for the wheels and suspension.
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